High void fraction multi-phase fluid flow meter

ABSTRACT

A high void fraction multi-phase fluid flow meter and method, wherein a first fluid flow path including a multi-phase flow measuring device disposed in series with a liquid flow restrictor is provided in parallel with a second fluid flow path including a gas flow measuring device. The presence of liquid flow in the flow meter is detected. When liquid flow is detected, a valve in the second fluid flow path operates to cut off fluid flow through the second fluid flow path. Otherwise the valve in the second fluid flow path operates to divert gas flow through the second fluid flow path. Alternatively, a negative pressure differential is produced across the second fluid flow path when liquid flow is present, by passing the incoming liquid flow through a jet pump nozzle, to prevent liquid flow into the second fluid flow path. A check valve is then disposed in the second fluid flow path to prevent backflow from the output of the multi-flow measuring device into the second fluid flow path. A computer outputs an indication of the liquid flow, typically oil flow and water flow, through the multi-phase flow meter, and the combined total amount of gas flow through the two flow meters.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of application Ser. No. 08/305,344,filed on Sep. 13, 1994, U.S. Pat. No. 5,589,642.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to multi-phase fluid flow meters and, inparticular, multi-phase fluid flow meters capable of accuratelymeasuring the flow of gas and liquid components of fluid flow over awide range of fluid concentrations from high gas fraction, where thefluid to be measured is substantially void of liquid, to fluidsincluding a substantial liquid component. The liquid component isfurther analyzed to provide flowrates of oil and water constituents.

2. Discussion of Background

In the oil industry, it is often necessary to measure the output of oilwells under varying conditions. In particular, oil wells typically havefluid outputs including gas and liquid components, with the liquidcomponents typically including water and oil. In order to reliablymeasure the quantity of each component in the oil well output, U.S. Pat.No. 5,099,697 discloses a multi-phase flow meter (MPFM) for measuringmulti-phase fluid flow, and particularly three phase fluid flowincluding gas, water and oil. However, for oil wells which produce largefractions of gas by volume, it is very difficult to measure accuratelythe flow of each fluid component as the MPFM must be sized for the gasvolumetric flow, while the liquid flow may be only a fraction of apercent. Under such circumstances which demand a wide operating dynamicrange and accuracy over the entire range of operation, including themeasuring of high void fraction fluids, i.e., high gas concentrationfluids, is compromised.

SUMMARY OF THE INVENTION

Accordingly, the object of this invention is to provide a novelmulti-phase fluid flow meter capable of operating with high accuracyover a wide range of fluid concentrations, including fluids having highvoid fractions.

This object and other objects are achieved according to the presentinvention by providing a new and improved high void fraction multi-phasefluid flow meter, including a first fluid flow path in which is disposeda multi-phase flow measuring device for measuring gas and liquid flowand a restrictor coupled in series with the multi-phase flow measuringdevice thereby to slow the flow of fluid through the measuring devicewhen the fluid includes liquid, a second fluid flow path provided inparallel with the first fluid flow path and such detection in which isdisposed a gas flow measuring device for measuring gas flow, liquid flowdetection device in said flow meter, device for diverting flow of gasinto the second fluid flow path when liquid flow is not detected in theflow meter, and device for outputting an indication of an amount ofliquid flow through the multi-phase flow measuring device and combinedtotal gas flow through the multi-phase flow measuring device and the gasflow measuring device.

In one embodiment of the flow meter of the present invention, the gasflow diversion device includes a valve disposed in series with the gasflow measuring device. A pressure drop across the restrictor is detectedand compared with a predetermined threshold, and if that threshold isexceeded, as occurs in the presence of liquid flow through therestrictor, the valve operates to cut off flow through the second fluidflow path.

In another embodiment, the presence of liquid flow at an inlet to thefirst fluid path is detected and the detected presence of liquid flow isused to actuate the valve to cut off flow through the second fluid flowpath. In this embodiment, the presence of liquid is typically detectedby passing the fluid being measured through a flow restricting nozzle,such as a nozzle of a jet pump, to produce a pressure drop in thepresence of liquid flow, with the pressure drop being detected byprocess instrumentation and utilized to actuate the valve to cut offflow through the second fluid flow path. Alternatively, a venturi deviceis provided at the inlet to the first fluid flow path. The pressure dropacross the throat of the venturi device is utilized to detect thepresence of liquid flow and based thereon actuate the valve to cut offflow through the second fluid flow path. Alternatively, the presence ofliquid flow may be measured by means of a densitometer which measuresthe density of the fluid at the inlet to the first fluid flow path andwhen the measured density indicates the presence of liquid flow, thevalve in the second fluid flow path is actuated to cut off flow throughthe second fluid flow path. On the other hand, when liquid flow is notdetected in any of the above embodiments, the valve opens to permit ordivert gas flow through the second fluid flow path so that gas flow fromthe second fluid flow path is metered by the gas flow measuring deviceand the gas flow through the first fluid flow path is metered by themulti-phase flow measuring device.

In another embodiment according to the present invention, the gas flowdiversion device includes a pressure reduction device, such as a flowrestricting nozzle of a jet pump, at a point upstream of the inlet tothe second fluid flow path. In the presence of liquid flow, a negativedifferential pressure is produced across the second fluid flow paththereby preventing fluid flow from entering the second fluid flow pathat its inlet. This negative differential pressure may create a reversecirculation flow from the multi-phase flow measuring device to thesecond fluid flow path. Therefore in a preferred embodiment, to preventa reverse circulation flow, a check valve is inserted in the secondfluid flow path. An expansion chamber and a de-mister, to knock off anymisty droplets carried by the gas, are preferably included in the secondfluid flow path at an inlet thereto.

Preferably, the multi-phase flow measuring device disposed in the firstfluid flow path is a three phase flow meter capable of measuring theconcentration of gas, water and oil in the fluid under measurement. Inthat case, the flow meter of the present invention outputs an indicationof the total water flow and the total oil flow measured by the threephase flow meter as well as the combined total gas flow measured by boththe three phase flow meter and the gas flow measuring device. However,the present invention also applies where a two-phase flow meter is usedto measure flow of gas and liquid (oil and water) in the first fluidflow path, and in that instance the present invention outputs anindication of liquid flow through the two-phase flow meter and combinedtotal gas flow through the two-phase flow meter and the gas flowmeasuring device.

The present invention further includes a new and improved method ofmeasuring multi-phase fluid flow of a fluid, including providing a flowmeter having first and second fluid flow paths in parallel with eachother, with the first fluid flow path including a multi-phase flowmeasuring device for measuring both gas flow and liquid flow and aliquid flow restrictor coupled in series with the multi-phase flowmeasuring device to slow the flow of liquid through the multi-phase flowmeasuring device, and the second fluid flow path including a gas flowmeasuring device for measuring gas flow; detecting liquid flow in theflow meter; controlling fluid flow through the first and second fluidflow paths by diverting fluid flow through the second fluid flow pathwhen the detecting step does not detect liquid flow in the flow meterand cutting off fluid flow through the second fluid flow path when thedetecting step detects liquid flow in the flow meter; and outputting anindication of the amount of liquid flow through the multi-phase flowmeasuring device and the combined total amount of gas flow through themulti-phase and gas flow measuring devices.

A first embodiment of the method invention includes detecting a pressuredrop across the flow restrictor provided in series with the multi-phaseflow measuring device and closing a valve to cut off flow through thesecond fluid flow path when the pressure drop detected exceeds apredetermined threshold.

In a second embodiment of the method of the present invention, thepresence of liquid flow is detected at an inlet to the first fluid flowpath, for example, by producing a pressure drop at the inlet upon thepresence of liquid flow, such as by passing the liquid under measurementthrough either a flow restricting nozzle or a venturi device having athroat, and detecting the resulting pressure drop across the flowrestricting nozzle or the venturi device in the presence of liquid flow.Alternatively, the method includes measuring one or more ofpredetermined properties of the fluid flowing at the inlet, such as thefluid's density, thermal conductivity, electrical conductivity, opticalopacity, or absorption of nuclear, electromagnetic or sound waves, orother properties such as taught in U.S. Pat. No. 4,774,680, e.g.,current, voltage, frequency, energy absorption, dielecric constant,capacitance, admittance and impedance, and closing the valve to cut offflow through the secondary flow measuring path when the measuredproperty indicates the presence of liquid flow.

In another embodiment of the method of the present invention, a negativedifferential pressure is created when liquid is present by means of ajet-pump. Backflow through the second fluid flow path is prevented bymeans of a check-valve in the second fluid flow path. An expansionchamber and a de-mister in the second fluid flow path collectscarry-over liquid droplets. The expansion chamber and de-mister can beadded to each of the embodiments of the present invention.

In a preferred embodiment of the method of the present invention, athree phase flow meter for measuring the flow of gas, water and oil isemployed as the multi-phase flow measuring device in the first fluidflow path. In the preferred embodiment, an indication of the amount ofwater flow and the amount of oil flow through the three phase flow meteris outputted, as well as an indication of the combined total amount ofgas flow through the three phase flow meter and the gas flow measuringdevice which is located in the second flow path. Alternatively, when atwo-phase flow measuring device is employed in the first fluid flowpath, the method of the present invention includes outputting anindication of liquid flow through the two-phase flow meter and anindication of combined total gas flow through the two-phase flow meterand the gas flow measuring device.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete appreciation of the invention and many of the attendantadvantages thereof will be readily obtained as the same becomes betterunderstood by reference to the following detailed description whenconsidered in connection with the accompanying drawings, wherein:

FIG. 1 is a schematic block diagram of a first embodiment of the highvoid fraction multi-phase fluid flow meter of the present invention;

FIG. 2 is a schematic block diagram of a second embodiment of the flowmeter of the present invention;

FIG. 3 is a schematic block diagram of a third embodiment of the flowmeter of the present invention;

FIG. 4 is a schematic block diagram of a fourth embodiment of the flowmeter of the present invention;

FIGS. 5a and 5b are time charts illustrating fluid flow through themulti-phase fluid flow measuring device in a first flow path of the flowmeter of the present invention both without and with, respectively, thepresence of a restrictor in the first fluid flow path; and

FIG. 6 is a schematic block diagram of a fifth embodiment of the presentinvention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to the drawings, wherein like reference numerals designateidentical or corresponding parts throughout the several views, and moreparticularly to FIG. 1 thereof, a first embodiment of the flow meter ofthe present invention includes a first fluid flow path 10 and a secondfluid flow path 12 connected in parallel to the path 10, both paths incommunication with an inlet connecting pipe 14 at inlets 11 to saidfirst flow path and 13 to said second flow path and an outlet connectingpipe 16 at outlets 15 to said first flow path and 17 to said second flowpath. The first fluid flow path 10 includes a multi-phase fluid flowmeter 18, preferably implemented as taught in commonly owned U.S. Pat.No. 5,099,697, coupled in series with a restrictor 20, the output of therestrictor 20 communicating with the output connecting pipe 16. In theembodiment disclosed in FIG. 1, the second fluid flow path 12 includes agas flow meter 22 coupled in series with a valve 24 which in turn iscoupled to the output of the first fluid flow path and the outputconnecting pipe 16.

As shown in FIG. 1, process instrumentation in the form of pressuresensors 26 and 28 are provided at the input and the output of therestrictor 20. Sensors 26 and 28 have respective outputs applied to acomputer 30 which determines the difference between the pressure sensedby the pressure sensors 26 and 28, compares the difference to athreshold, and actuates the valve 24 when the pressure differenceexceeds a predetermined value indicative of liquid flow through therestrictor 20. Computer 30 otherwise maintains the valve 24 open topermit gas flow through the second fluid flow path when the detectedpressure drop across the restrictor 20 is less than the predeterminedthreshold, which is indicative of substantial gas flow through therestrictor 20.

The present invention takes advantage of the recognition that in mostcases, droplets of liquid in the fluid flow tend to bunch together (ashappens in klystrons chromatographs, etc.) and would appear at the flowmeter 18, in the absence of the restrictor 20, as a short duration spikeof mainly liquid mixed with gas, as shown in FIG. 5a. However, it isdifficult to measure accurately the amount of liquid flow in highvelocity short duration spikes as shown in FIG. 5a. This is true becauseof the finite response time of the flow meter 18 and because thepossibility of damaging flow meter 18. According to the presentinvention, the difficulty is overcome by slowing the fluid spike toproduce a liquid slurry, i.e., by packing more liquid in the flow path10. Therefore, according to the present invention, the restrictor 20 isprovided to "iron out" the sharp spikes so that the fluid flow appearsat the flow meter 18 as a slug of decreased velocity and amplitude andincreased time duration. Since the input connecting pipe 14 is notpacked with incompressible fluid, i.e., is packed with a gas/liquidmixture, restrictor 20 prolongs the duration of the liquid slug throughthe flow meter 18 by packing more liquid upstream of the flow meter 18.Thus, the restrictor 20 slows the flow of the liquid-gas mixture throughthe flow meter 18 and causes it to pack-up in front of the flow meter 18as fluid slugs shown schematically in FIG. 5b.

Typically, the restrictor 20 is dimensioned to limit the maximum liquidflow through the flow meter 18 to 150% of the full-scale rating of thevolumetric flow meter section of flow meter 18. For example, if flowmeter 18 is implemented according to U.S. Pat. No. 5,099,097, it wouldinclude two volumetric flow meter sections separated by a restriction.In that instant, the restrictor 20 is dimensioned to limit the maximumliquid flow to 150% of the full scale rating of the smaller of the twovolumetric flow meter sections. If on the other hand, a multi-phase flowmeter as taught in copending U.S. patent application Ser. No.08/852,544, incorporated by reference herein, which includes avolumetric flow meter section in series with a momentum flow metersection, is used, then restrictor 20 is sized to limit liquid flow to150% of the full-scale rating of the volumetric flow meter section.Thus, in the present invention, the flow meter 18 is sized for themaximum liquid flow and the flow meter 22 is sized for the maximum gasflow. At high void fraction, e.g., 95% void fraction, the superficialgas flow is much higher than the superficial liquid flow, i.e.,approximately 20:1 higher, and the flow meters 22 and 18 are sizedaccordingly.

Further elaborating on the role of the restrictor 20, as thedifferential pressure p across the restrictor is proportionate to thefluid velocity squared (V²) times the density (D), i.e., p=DV², sincethe density of the gas is quite small in comparison to the density ofthe liquid, gas flow through the restrictor 20 will hardly be affected,whereas since the density of the liquid is much greater than the densityof the gas, the pressure loss for the liquid, for the same velocity, ismuch greater than the pressure loss for gas passing through therestrictor 20. Thus, as previously indicated, the restrictor 20 slowsdown liquids, and not gases, and results in a measurable pressure dropin the presence of liquid. Since the liquid flow peaks are "ironed out"as shown in FIG. 5b, the flow meter 18 can thus be made much smallerthan would otherwise be necessary to accommodate the peak superficialgas flow rate, as the restrictor 20 determines the maximum flow rate.

According to the present invention as above indicated, the pressuresensors 26, 28 and the computer 30 are utilized to detect the presenceof liquid flow through the restrictor 20 and actuate the valve 24 to cutoff flow through the gas flow meter 22 so that all the fluid from theinput connecting pipe 14 passes through the multi-phase flow meter 18 inthe presence of liquid flow. In the presence of substantial gas flow andinconsequential liquid flow, i.e., in the presence of high void fractionfluid flow, little pressure drop is detected across the restrictor 20,resulting in gas flow through both the first and second fluid flow pathsand gas measurement by both the multi-phase flow meter 18 and the gasflow meter 22. In the operation as above described, the restrictor slowsdown the liquids, but not the gases. The flow meter 18 can thus bedesigned to measure maximum liquid flow rates much lower than wouldotherwise be required if it had to measure the maximum gas flow rate aswell. Restrictor 20 determines the maximum liquid flow rate as a resultof which flow meter 18 experiences much smaller flows. This cannot bedone in a single-phase fluid flow in which the line 14 would have nospare space to pack more liquid in it, but does apply to multi-phaseflow including gas flow.

Valve 24 in FIG. 1 is shut when the differential pressure acrossrestrictor 20 exceeds a predetermined value, i.e. when a mixture ofliquid and gas is flowing through it. Flow path 12 is bigger than flowpath 10, and as the liquid is substantially incompressible, the positionof restrictor 20 is immaterial whether it is upstream or downstream offlow meter 18. The advantage of inserting it downstream is that absolutepressure in flow meter 18 is maintained higher, thus it sees a smalleractual gas flow rate. The disadvantage is that more liquid will enterby-pass flow path 12 before the valve 24 will shut. The vertical riserof by-pass path 12 requires a larger differential pressure than thedifferential pressure across the restrictor 20. Valve 24 then will shutlong before the riser fills up preventing flow of liquid through path12.

Data on the flow rates of gas, water and oil passing through the flowmeter 18 are applied to the computer 30 along with the outputs of thepressure sensors 26 and 28. The computer 30 controls activation of thevalve 24 to allow the high velocity gas to flow through the second fluidflow path 12 which serves as a by-pass for the high velocity gas. Theflow of gas through the second fluid flow path 12 is metered by the gasflow meter 22, the output of which is also applied to the computer 30.At high gas flow rate where the flow meter 18 runs at 150% of its normalgas flow rate, the differential pressure across the restrictor isrelatively small, so the computer 30 causes the valve 24 to bemaintained open and permits excess gas to be metered by the gas flowmeter 22. The computer 30 then outputs an indication of the liquid flow,i.e., water flow and oil flow measured by the flow meter 18, as well asa combined total gas flow measured by the flow meters 18 and 22. Where atwo-phase flow meter is used for the flow meter 18, then the computeroutputs an indication of liquid flow through the flow meter 18 as wellas combined total gas flow through the flow meters 18 and 22.

FIG. 2 shows a second embodiment of the invention which likewise resultsin the cut off of flow through the gas flow meter 22 upon detection ofthe presence of liquid flow in the flow meter. In the embodiment of FIG.2, however, operation of the valve 24 is controlled based on thepressure drop produced by liquid flow through the nozzle 32 of a jetpump 34 which is installed upstream of flow meter 18. In FIG. 2, thevalve 24 is controlled by the suction created by the jet pump 34 whenliquid passes through the jet pump 34. When liquid flows through thenozzle 32 of the jet pump 34, a lower pressure is created in the chamber36. Valve 24 is schematically shown in FIG. 1 and can be either apneumatic or hydraulic diaphragm valve, or a solenoid operated valve. Asshown in FIG. 2, process instrumentation in the form of pressure sensor37, shown as "P₃ ", is housed in chamber 36, and is further operable tosend a control signal to valve 24. Valve controller 25 is coupled tovalve 24 and capable of receiving a signal from pressure sensor 37indicative of the measured pressure, such that valve 24 is actuated whenthe measured pressure exceeds a predetermined value. The valve 24 isnormally open, but shuts off when liquid flow is detected. The advantageof using a normally open valve is that if there is a power failure, theline is not blocked to gas flow by the flow meter. The reduced pressureproduced by liquid flow is utilized to shut off the reverse acting valve24, causing the valve 24 to cut off flow through the second fluid flowpath 12. When gas passes through the nozzle 32, pressure in the chamber36 is essentially the same as in the main line 38 feeding the jet pump34, and valve 24 opens under the action of a reverse acting spring (notshown). Thus, liquid-gas mixture slugs are metered by the multi-phaseflow meter 18 while high flowing gas is metered by both the flow meters18 and 22. As in the first embodiment, the computer 30 outputsindications of the water flow and the oil flow through the multi-phaseflow meter 18 and the combined total gas flow through the flow meters 18and 22 when a three-phase flow meter 18 is employed and otherwiseoutputs an indication of the liquid flow through the flow meter 18 andthe combined total gas flow through the flow meters 18 and 22 when atwo-phase flow meter 18 is employed.

In another embodiment shown in FIG. 3, the jet pump 34 is replaced by aventuri 40 having a throat 42. In the FIG. 3 embodiment, the lowpressure created at the throat 42 of the venturi operates the reverseacting valve 24 in a similar manner to the operation of the jet pump ofFIG. 2. The advantage of this embodiment is that very little pressure islost across the venturi 40 and most of the pressure dropped at thethroat 44 is recovered by the expander section of the venturi downstreamof the throat 42.

In FIG. 4, the venturi is replaced with a void fraction meter 44, whichoperates valve 24 in a similar manner as described with respect to theembodiment of FIG. 1. Void fraction meter 44 can be a device measuringthe density of the fluid (nuclear, differential pressure, etc.) or otherknown void fraction meter devices. There are many types of void fractionmeters: e.g. dielectric, electrical or thermal conductivity, optical,etc. They all measure how dense the fluid is. Use of a density meter isreserved for meters that measure the density of the fluid inweight/volume units.

FIG. 6 illustrates another embodiment of the present invention, and inthis embodiment the differential pressure across the flow restrictor 32of the jet pump 34 in the chamber 36 is used to prevent liquid flowthrough the second flow path 12. As shown in FIG. 6, the flow restrictor32 is a nozzle. The pressure in line 12 is substantially the same as atthe outlet of MPFM 18. The flow restrictor 32 of Jet Pump 34 creates asuction (lower pressure) which would suck liquid back from the outlet ofMPFM 18, if this were not prevented. When a slug of liquid-gas mixturegoes through the jet 34, it may create a pressure drop larger than thepressure drop across the multi-phase flow meter 18. Since differentialpressure or suction is used to inhibit liquid flow from entering theinlet of the second fluid flow path, instead of a valve 24 as shown inFIGS. 1-4, no separate liquid flow detection device is needed with thisembodiment of the invention. In a preferred embodiment, a check valve24₁ is employed in the by-pass fluid flow path 12. Check valve 24₁closes to prevent backflow from the output of the flow meter 18 whichmight otherwise result due to the pressure drop caused by the flow ofliquid through the nozzle 32. Thus, backflow through the flow path 12from the output of the flow meter 18 is prevented by the check valve.The fluid mixture passes through to the multi-phase fluid flow meter 18and to the output connecting pipe 16. In the presence of gas passingthrough the flow restrictor 32, the differential pressure in the chamber46 is quite small compared with that in the by-pass path or second fluidflow path 12, and most of the flow goes through the by-pass where it ismetered by the gas flow meter 22.

In a preferred embodiment, the invention comprises an expansion chamber46, as shown in FIG. 6. The expansion chamber 46 provided upstream ofthe flow meter 22 slows the flow of fluid to the flow meter 22, andallows any droplets of liquid carryover to drop back into the chamber36. Adding a de-mister 48 enhances the effect. The expansion chamber 46,with or without a de-mister 48, can be used to advantage in any of theembodiments of the present invention.

Obviously, numerous modifications and variations of the presentinvention are possible in light of the above teachings. It is thereforeto be understood that within the scope of the appended claims, theinvention may be practiced otherwise than as specifically describedherein.

What is claimed as new and desired to be secured by Letters Patent ofthe United States is:
 1. A multi-phase fluid flow meter comprising:a. afirst fluid flow path comprising a first flow measuring device capableof measuring gas and liquid flow, an inlet and an outlet; b. a secondfluid flow path in parallel with said first fluid flow path, having aninlet and connected to said first fluid flow path near the inlet of saidfirst fluid flow path and having an outlet connected to said first fluidflow path near the outlet of said first fluid flow path, and furthercomprising a second flow measuring device capable of measuring gas flow;and c. a device comprising a flow chamber, said device installed at thejunctions of the inlets to said first and second flow paths, said flowchamber comprising a flow restrictor such that the flow of liquidthrough said flow restrictor creates a differential pressure thatinhibits liquid flow from entering said second fluid flow path.
 2. Theflow meter of claim 1, further comprising an indicator capable ofindicating the amount of liquid through said first flow measuring deviceand the combined total amount of gas flow through said first and secondflow measuring devices.
 3. The flow meter of claim 1, further comprisinga check valve installed in said second fluid flow path and configured toprevent backflow when sufficient suction is created at said flowrestrictor to cause a backflow through said second fluid flow path. 4.The flow meter of claim 1, further comprising an expansion chamberinstalled in said second fluid flow path upstream of said device.
 5. Theflow meter of claim 4, further comprising a demister contained withinsaid expansion chamber, said demister being capable of removing mistfrom fluid flowing through said demister.
 6. The flow meter of claim 1,further comprising a jet pump in said flow chamber, said jet pumpcomprising said flow restrictor.
 7. A multi-phase flow metercomprising:a. a first fluid flow path comprising a first flow measuringdevice capable of measuring gas and liquid flow, an inlet and an outlet;b. a second fluid flow path in parallel with said first fluid flow path,having an inlet and connected to said first fluid flow path near theinlet of said first fluid flow path and having an outlet connected tosaid first fluid flow path near the outlet of said first fluid flowpath, and further comprising a second flow measuring device capable ofmeasuring gas flow; c. a device comprising a flow chamber, said deviceinstalled at the junctions of the inlets to said first and second flowpaths, said flow chamber comprising a flow nozzle installed in said flowchamber such that the flow of liquid through said flow nozzle creates asuction that inhibits fluid flow from entering said second fluid flowpath; and d. an indicator capable of indicating the amount of liquidthrough said first flow measuring device and the combined total amountof gas flow through said first and second flow measuring devices.
 8. Theflow meter of claim 7, further comprising a check valve installed insaid second fluid flow path and configured to prevent backflow oncesufficient suction is created at said flow restrictor to cause abackflow through said second fluid flow path.
 9. The flow meter of claim7, further comprising an expansion chamber installed in said secondfluid flow path upstream of said second flow measuring device.
 10. Theflow meter of claim 7, further comprising a jet pump in said flowchamber, said jet pump comprising said flow restrictor.
 11. Amulti-phase fluid flow meter comprising:a. a first fluid flow pathcomprising a first flow measuring device capable of measuring gas andliquid flow, and a restrictor coupled in series with said first flowmeasuring device, such that the flow of fluid through said first flowmeasuring device is slowed when said fluid includes liquid, and saidfirst fluid flow path further comprising an inlet and an outlet; b. asecond fluid flow path in parallel with said first fluid flow path,having an inlet and connected to said first fluid flow path near theinlet of said first fluid flow path and having an outlet connected tosaid first fluid flow path near the outlet of said first fluid flowpath, and further comprising a second flow measuring device capable ofmeasuring gas flow; c. a liquid flow detection device in said flow meterlocated upstream of the inlets of said first and second fluid flowpaths; d. a device for diverting gas flow into said second fluid flowpath when liquid flow is not detected by said liquid flow detectiondevice and said diverting device further being capable of preventingfluid flow from entering said second fluid flow path at its inlet whenliquid flow is detected by said liquid flow detection device; and e. anindicator capable of indicating the amount of liquid through said firstflow measuring device and the combined total amount of gas flow throughsaid first and second flow measuring devices.
 12. The flow meter ofclaim 11, wherein said device for diverting gas flow comprises a valvedisposed in said second fluid flow path and operable to cutoff flow insaid second fluid flow path when liquid flow is detected by said liquidflow detection device.
 13. The flow meter of claim 12, wherein saidliquid flow detection device comprises process instrumentation formeasuring a pressure drop across said restrictor and closing said valvewhen the pressure drop across said restrictor exceeds a predeterminedthreshold.
 14. The flow meter of claim 12, wherein said liquid flowdetection device comprises process instrumentation for detecting thepresence of liquid flow at the inlet to said first fluid flow path andfor closing said valve to cutoff flow through said second fluid flowpath when the presence of liquid flow is detected at said inlet.
 15. Theflow meter of claim 14, wherein said process instrumentation is apressure sensor.
 16. The flow meter of claim 14, wherein said liquidflow detection device comprises a flow restrictor installed in the inletof said first fluid flow path, said flow restrictor being capable ofproducing a pressure drop at said inlet when liquid flow is present atsaid inlet.
 17. The flow meter of claim 16, wherein said flow restrictoris a jet pump.
 18. The flow meter of claim 11, wherein said liquid flowdetection device comprises:a. a flow restriction nozzle installedupstream of said inlets to said first and second fluid flow paths; b. apressure sensor capable of measuring the pressure near the outlet ofsaid flow restriction nozzle; and c. a valve controller coupled to saidvalve and capable of receiving a signal from said pressure sensorindicative of measured pressure, such that said valve is closed when themeasured pressure exceeds a predetermined value.